Improve contributing instructions (#4504)

README.md

@@ -137,10 +137,14 @@ Lemmy is made possible by a generous grant from the [NLnet foundation](https://n
 
 ## Contributing
 
+Read the following documentation to setup the development environment and start coding:
+
 - [Contributing instructions](https://join-lemmy.org/docs/contributors/01-overview.html)
 - [Docker Development](https://join-lemmy.org/docs/contributors/03-docker-development.html)
 - [Local Development](https://join-lemmy.org/docs/contributors/02-local-development.html)
 
+When working on an issue or pull request, you can comment with any questions you may have so that maintainers can answer them. You can also join the [Matrix Development Chat](https://matrix.to/#/#lemmydev:matrix.org) for general assistance.
+
 ### Translations
 
 - If you want to help with translating, take a look at [Weblate](https://weblate.join-lemmy.org/projects/lemmy/). You can also help by [translating the documentation](https://github.com/LemmyNet/lemmy-docs#adding-a-new-language).